HMS87C1808B Datasheet, PDF (58/99 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

HMS87C1X04B/08B/16B
The SPI allows 8-bits of data to be synchronously transmitted and
received. To accomplish communication, typically three pins are
used:
- Serial Data In
- Serial Data Out
- Serial Clock
RC5/SIN
RC6/SOUT
RC4/SCK
In addition to those pins, a fourth pin may be used when in a mas-
ter or a slave mode of operation:
- Serial Transfer Ready
RC3/SRDYIN/SRDYOUT
The serial data transfer operation mode is decided by setting the
SM1 and SM0 of SPI Mode Control Register, and the transfer
clock rate is decided by setting the SCK1 and SCK0 of SPI Mode
Control Register as shown in Figure 13-1 . And the polarity of
transfer clock is selected by setting the POL.
The bit SRDY is used for master / slave selection. If this bit is set
to “1” and SCK[1:0] is set to “11”, the controller is performed to
slave controller. As it were, the port RC3 is served for SRDY-
OUT.
SIOST
SCK
(POL=1)
SCK
(POL=0)
SOUT
SIN
SPIF
(SPI Int. Req)
D0
D1
D2
D3
D4 D5
D6
D7
D0
D1
D2
D3
D4
D5
D6
D7
Figure 13-2 SPI Timing Diagram (without SRDY control)
SRDY
SIOST
SCK
(POL=1)
SCK
(POL=0)
SOUT
SIN
SPIF
(SPI Int. Req)
D0
D1
D2
D3
D4 D5
D6
D7
D0
D1
D2
D3
D4
D5
D6
D7
Figure 13-3 SPI Timing Diagram (with SRDY control)
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SEP. 2004 Ver 1.03